A vertical bearing device that supports a rotating shaft member of a rotary machine such as a large generator and electric motor is publicly known. The vertical bearing device supports both of thrust load in the axial direction and radial load in the radial direction, of the rotating shaft member that extends vertically in the direction of gravitational force. Bearing parts corresponding to axial and radial load of the vertical bearing device become heated by rotation of the rotating shaft member, and therefore need to be appropriately cooled. Conventionally, a vertical bearing device has been adopting an air cooler that cools the whole device mainly by air-blowing, or an oil cooler that cools lubricating oil on the outside. When an air cooler is used, a fan that rotates with the rotating shaft member is used to cool the bearing device by an air flow generated by the fan (Japanese Patent Laid-Open No. 2003-293977). Instead, when an oil cooler is used, rotation of the rotating shaft member is used to discharge lubricating oil that lubricates the bearing part to the outside, and the lubricating oil is circulated between the bearing device and the cooler to thereby cool the bearing device (Japanese Patent Laid-Open No. 5-106636).
As described above, the vertical bearing device supports the rotating shaft member on each of a thrust bearing part in the axial direction and a journal bearing part in the radial direction. Hence, heat resulting from rotation of the rotating shaft member occurs in each of the thrust bearing part and the journal bearing part. The generated heat is absorbed by lubricating oil filling the inside of the vertical bearing device, and the lubricating oil having absorbed the heat is cooled by air or an external cooler.
Accordingly, if circulation of lubricating oil is hindered, the lubricating oil does not absorb the generated heat appropriately. This may cause a rise in temperature of the thrust bearing part or the journal bearing part. Increased temperature of the bearing parts causes a problem of seizing of the thrust bearing part or the journal bearing part. Meanwhile, a pump device or the like for circulating lubricating oil may be provided to prompt circulation of lubricating oil. However, this causes a problem of complication of maintenance due to complication of structure, and also deterioration in efficiency since driving power needs to be ensured.